The present invention generally relates to magnetic recording and reproducing, and more particularly, to a magnetic recording and reproducing apparatus in which it is required to maintain a synchronous relationship, for example, between reproducing data and recording data.
Recently, in sites for recording music and the like, there have been widely adopted recording systems which employ many microphones to correspond to individual musical instruments, or those in which musical instruments are individually played without playing all the musical instruments simultaneously for recording at each playing. For the recording systems as referred to above, there has been generally employed a multi-channel magnetic recording and reproducing apparatus in which channels are individually allocated to respective microphones and musical instruments for recording, and in a recent trend, the recording system of the magnetic recording and reproducing apparatus is being shifted from the analog system to the digital system.
In the recording by the multi-channel magnetic recording and reproducing apparatus as described above, even in the case where the playing by the respective musical instruments has been simultaneously recorded, it is rare to complete recording by the recording at one time, but normally, so-called punch in/out is effected in which the predetermined performance of a specific channel is repeatedly recorded until satisfaction is achieved. Meanwhile, in the case where a simultaneous recording is not effected, a synchronous recording is made in which playing by another musical instrument is recorded in a different channel, while the sound of the channel recorded earlier is being reproduced. In the multi-channel magnetic recording and reproducing apparatus for effecting the function as described above, it is an essential function to maintain synchronization among the respective channels on the magnetic tape at high accuracy.
In the multi-channel magnetic recording and reproducing apparatus of the analog type, a magnetic head of an induction type is employed, and it is possible to effect the recording and reproducing by the same magnetic head, whereby a high synchronizing accuracy may be readily realized accordingly.
On the contrary, in the multi-channel magnetic recording and reproducing apparatus of the digital system, it is so arranged that a delay is produced between the time at which data is inputted into a circuit or it is outputted from the circuit and the time at which data is recorded on a magnetic tape by the magnetic head or it is reproduced from the magnetic tape. Therefore, in the recording and reproducing by the single head, for example, the punch in/out referred to earlier can not be properly effected. Accordingly, the magnetic recording and reproducing by the digital system is realized by providing at least one reproducing head and one recording head along the travelling direction of the magnetic tape in that order at a predetermined interval.
Moreover, in the multi-channel magnetic recording and reproducing apparatus of the digital system as described above, it is necessary to control a moving distance of the magnetic tape between the preceding reproducing head and the recording head, i.e. the distance on a tape path in a range permissible by a digital signal processing format. A mechanical adjusting mechanism for the above purpose is disclosed, for example, in Japanese Patent Laid-Open Publication Tokkaisho No. 60-59561.
Meanwhile, in the magnetic recording and reproducing apparatuses in general, high density recording with high reliability, and consequent reduction in the consumption of recording medium and smaller size of the apparatus, etc. are required.
The request for the high density recording as described above has been satisfied by attempting to achieve higher density of the track pitch, and reduction of the shortest recording wavelength. More specifically, in the multi-channel magnetic recording and reproducing apparatus, it is necessary to allocate the channel for each microphone or musical instrument, and furthermore, in the apparatus of the digital system, it is required to lower error rate of the data by dispersing into a plurality of tracks for recording information of one channel, thus inevitably necessitating to provision of a large number of tracks for the purpose. As a result, the track pitch becomes, for example, smaller than 100 .mu.m, which is a marked reduction as compared with that in the conventional apparatuses of the analog system. Moreover, the shortest recording wavelength is now in the order of about 0.6 to 0.7 microns.
In order to achieve a high density recording as described above in the multi-channel magnetic recording and reproducing apparatus, it is necessary for the magnetic tape to travel on the order of microns while maintaining the predetermined positional relationship with respect to the magnetic head. Furthermore, it is also required to achieve a favorable contact state of the magnetic tape with respect to the magnetic gap of the magnetic head, i.e. to obtain a good "head to tape contact" of the head by reducing spacing loss or azimuth loss which are the conditions specific to the magnetic recording.
As described above, the conditions required for the multi-channel magnetic recording and reproducing apparatus of the digital system are as follows.
(1) The distance on the tape path between the preceding reproducing head and the recording head should be accurately controlled.
(2) With respect to the travelling of the magnetic tape, variation in a widthwise direction should be controlled at an accuracy on the order of microns.
(3) A favorable "head to tape contact" should be maintained.
For satisfying the conditions as described above, the multi-channel magnetic recording and reproducing apparatus conventionally adopted is arranged as follows.
In order to accurately control the distance on the tape path between the preceding reproducing head and the recording head, the arrangement as disclosed, for example, in the earlier-mentioned Japanese Patent Laid-Open Publication Tokkaisho No. 60-59561 is employed. Moreover, for causing the magnetic tape to accurately travel on the order of microns, a tape guide is provided within the tape path, to thereby to control the magnetic tape. Furthermore, for maintaining a favorable "head touch", it is necessary to adjust the attitudes or postures, and height of the magnetic heads in the azimuth direction, hinged direction and tilting direction, etc., with respect to the tape travelling face, and the individual magnetic heads are mounted through suspension mechanisms having the adjusting functions as stated above.
However, in the conventional arrangement as described above, since various adjusting mechanisms must be provided around the magnetic heads for recording and reproduction and the tape guide, size reduction in the vicinity of the magnetic heads and the tape guide is undesirably restricted, thus obstructing achievement of a compact size of the apparatus on the whole. Particularly, in the magnetic recording and reproducing apparatus which employs the magnetic tape, although it is essential to shift from the open reel type to the cassette type from the viewpoint of operation , the difficulty in the size reduction around the magnetic head and the tape guide presents a large obstruction for the shifting into the cassette construction of the magnetic tape.